1. Field of the Invention
The present invention relates to an apparatus and method for forming a layer of particulate material within a fibrous web. More particularly, the present invention relates to an apparatus and method for forming a discrete layer of high absorbency particles within an absorbent pad composed of hydrophilic fibers.
2. Description of the Related Art
Absorbent articles, such as disposable infant diapers, feminine care products, incontinence garments and the like, have included high-absorbency particles in their absorbent pad to increase the absorbent capacity of the article and to reduce the bulkiness of the article. Particular absorbent article designs have concentrated high absorbency particles in selected regions of the absorbent pad. For example, U.S. Pat. No. 5,030,314 to Lang describes an apparatus which includes a roll having discrete indentations for receiving particulate material and selectively transferring the material to a web. In some conventional arrangements, the high absorbency particles, such as superabsorbent polymers, have been substantially uniformly mixed with the absorbent fibers located within the selected layers. In other arrangements, the high absorbency particles have been substantially isolated in layers, zones or pockets within the absorbent pad with the high absorbency particles being substantially unmixed with the absorbent fibers.
Various devices and processes have been employed to manufacture the absorbent articles. Air forming techniques for forming webs of hydrophilic fibers, such as woodpulp fibers, are well known in the art. In addition, it is well known that high absorbency particles, such as superabsorbent polymers, may be mixed with the hydrophilic fibers during an airlaying process to form an absorbent web. It is also well known that the high absorbency particles may be limited to a predetermined portion of the thickness of the absorbent web.
Conventional apparatus and methods for forming absorbent webs, such as those described above, have not been sufficiently satisfactory. For example, the devices may be overly complex and expensive and may not provide the capability to form patterned or intermittent, discrete layers of particulate materials. The rate and consistency of delivery of the particulate material may not be adequately controlled, and the systems may be excessively sensitive to changing variables in the process.